The present invention relates in general to the design of a threaded plastic closure which is used to close off the outlet opening of an open-topped container. More specifically the present invention relates to the design of a threaded closure which is constructed so as to provide a tamper-evident arrangement as well as being made child-resistant. The tamper-evident closure of the present invention is disclosed in two primary embodiments, one with the child-resistant arrangement and one without the child-resistant arrangement. However, it would be possible with the mold design which is used for the present invention to construct the inner cap without the tamper-evident feature and thereby effectively create four different configurations from the same basic mold design.
The child-resistant arrangement is achieved by the use of an outer cap which is concentrically configured relative to an inner cap and is snapped over the inner cap so as to be retained in its desired relationship with the inner cap. The elimination of the outer cap removes the intended child-resistant capability.
Plastic, tamper-evident threaded closures have been available for a number of years and are thus regarded as being well-known to a person of ordinary skill in the art. These closures employ a variety of features for various reasons and applications. The tamper-evident arrangements likewise represent a variety of design approaches, though there are quite often certain similarities. The underlying objective is to enable the user of the product to determine whether the initially filled and closed container has been improperly opened which could indicate a tampering attempt. Tamper-evident closures have commonly been made of aluminum or plastic, with one type of closure including an upper cap portion and a lower security ring or band attached to the cap portion by a failure line. When the two-piece cap is removed, the closure breaks along the failure line, leaving the ring separate from the cap portion.
While this art is quite crowded, the following listed patent references are believed to provide a representative sampling of earlier tamper-evident closures which relate generally to the present invention:
______________________________________ PATENT NO. PATENTEE ISSUE DATE ______________________________________ 4,546,892 Couput Oct. 15, 1985 4,721,218 Gregory et al. Jan. 26, 1988 4,801,030 Barriac Jan. 31, 1989 4,801,031 Barriac Jan. 31, 1989 4,913,300 Wiedmer et al. Apr. 3, 1990 4,971,212 Kusz Nov. 20, 1990 4,978,016 Hayes Dec. 18, 1990 4,978,017 McBride Dec. 18, 1990 5,090,788 Ingram et al. Feb. 25, 1992 5,107,998 Zumbuhl Apr. 28, 1992 5,129,530 Fuchs Jul. 14, 1992 5,295,600 Kowal Mar. 22, 1994 5,310,069 Ingram et al. May 10, 1994 5,397,009 Salmon et al. Mar. 14, 1995 5,400,913 Kelly Mar. 28, 1995 4,884,706 Julian Dec. 5, 1989 5,080,246 Hayes Jan. 14, 1992 5,145,078 Hannon et al. Sep. 8, 1992 5,197,620 Gregory Mar. 30, 1993 5,271,512 Ekkert Dec. 21, 1993 4,653,657 Papavasilopoulos Mar. 31, 1987 4,938,370 McBride Jul. 3, 1990 4,981,230 Marshall et al. Jan. 1, 1991 5,004,112 McBride Apr. 2, 1991 5,252,068 McCandless Sep. 7, 1993 ______________________________________
While the foregoing references should adequately summarize the state of the art, there are other aspects of the present invention which deserve additional consideration relative to any earlier references which may be relevant. One feature of the present invention is the addition of an outer cap so as to convert the basic closure, whether tamper-evident or not, into a child-resistant closure. A unique arrangement of ratchet teeth in the outer circumferential periphery of the outer cap in combination with circumferential depressions in the upper surface of the inner cap provide the means of advancing the inner cap onto the threaded outlet opening through ratchet and depression engagement. Retrograde removal of the inner cap, which would be achieved in the normal manner of counterclockwise rotation of the outer cap, is accomplished by other means which do not involve ratchet tooth engagement. Removal of the inner cap according to the present invention requires ovalizing of the outer cap so as to draw portions of the outer cap into engagement with the inner cap, at which point axial ribs are drawn into abutment in order to transfer rotational torque from the outer cap to the inner cap.
The user of inner and outer caps in order to provide what is referred to as a type of child-resistant closure is disclosed in U.S. Pat. No. 4,598,833, issued Jul. 8, 1986 to Herr, and by U.S. Pat. No. 5,280,842, issued Jan. 25, 1994 to Koo. The Herr patent discloses a child-resistant, tamper-evident closure having nested inner and outer caps with ratchet teeth on the inner facing skirt walls of the respective caps to cooperate to fasten the closure onto the container, and ratchet teeth on the inner facing top walls of the respective caps for removal of the closure upon simultaneous application of torque and a downward force. The Koo patent discloses a two-piece child-resistant closure which utilizes a ratchet feature to screw on the closure. One feature of this design is a particular ratchet configuration which includes a specific placement of the elements thereof in order to provide negligible reverse torque during undepressed counterclockwise rotation of the outer closure member. In this application, negligible reverse torque is defined as the torque caused by frictional contact of the outer and inner cap members when the undepressed closure is turned in the removal direction and this is insufficient to cause the undesired or accidental removal of the closure from the container.
The top wall of each cap in these two listed references is a solid circular panel as contrasted with an annular ring-shaped top wall which is consistent with the present invention. Further, the ratchet teeth on each cap are arranged in a radiating pattern across the corresponding surface of the top wall. In order to accommodate such a ratchet tooth pattern, the top wall of each cap needs to be of a solid circular shape rather than being of an annular-ring shape. The presence of a solid top wall for each cap results in the use of more material, increased closure weight, and makes the desired ovalizing of the cap a significantly more difficult manipulation. With a solid circular top wall the wall material must deform in some direction if the outer cap is to be radially compressed into an oval shape. This requires more force than what is required with a substantially open top wall. However, since the retrograde removal of the corresponding inner caps of these two references involves ratchet tooth engagement and in one instance simultaneous downward force, ovalizing of the outer cap is not a consideration. Since the Koo closure receives a downward axial force which must be exerted on the top surface of the outer cap in order to remove the inner cap, this would provide another reason for requiring a solid top wall as part of the outer cap.
In contrast, the present invention uses a unique outer cap design with only a partial top wall having an annular-ring shape. The annular ring shape of the top wall portion of the present invention thereby defines and leaves open the center area. The ratchet teeth which are present on the outer cap are disposed on the underside of the partial top wall portion and extend in the direction of the inner cap. The pattern of ratchet teeth on the outer cap is circumferential rather than radial and this permits the center portion of the outer cap to be left open, thereby reducing the weight and the amount of material. The open center portion of the outer cap also simplifies to some extent ovalizing of the outer cap which is the required manipulation in order to be able to remove the inner cap.
Turning now to caps and closures which incorporate some type of tamper-evident feature, a break-away ring is often employed. For the most part these closure designs use inwardly and upwardly extending tabs such as disclosed in the Herr '833 patent. This style of tabs requires some type of post-forming operation after the cap is initially molded in order to orient the tabs in the desired inward and upward direction. As perceived by Herr, "conventional molding processes are not capable of producing a closure having the preferred tabs extending upwardly and inwardly as described above" (Herr '833 patent, column 5, lines 27-29). Consequently, in a separate operation, the tabs are bent radially inwardly and upwardly, with heat being applied to the tab joints.
It is obviously important to get the tabs oriented in the desired manner as efficiently and as cost effectively as possible. Notwithstanding the descriptions in the Herr '833 patent, U.S. Pat. No. 5,007,545, issued Apr. 16, 1991 to Imbery, Jr., describes a molding method which does not require side action mold parts nor any subsequent forming operations. The sequential molding steps are illustrated in FIGS. 9-13 of the Imbery, Jr. patent.
U.S. Pat. No. 4,997,097, issued Mar. 5, 1991, to Krautkramer discloses a closure with inwardly and upwardly directed tabs. However, there is no specific mention of the molding process, nor whether a post-forming operation is required to achieve this particular tab orientation. The Krautkramer patent discloses a design which is otherwise believed to be conventional as to the general style and function of the tabs.
The present invention provides a unique manufacturing method and a unique resulting configuration for a series of upwardly directed tabs. As the inner cap is molded, a circumferential series of tabs are initially formed in a downwardly-extending orientation. However, as the molding process is concluded and the cap is ejected from the mold, the tabs are bent upwardly and tucked inside an annular bead which is integrally formed as part of the sidewall of the inner cap. The annular bead which is actually an offset wall portion holds the bent tabs in this desired configuration, thereby presenting the tabs in an operable orientation so as to provide a tamper-evident feature to the present invention. The tabs are also placed in engagement with axial ribs disposed around the neck finish of the corresponding container on which the cap is used to provide an anti-backoff feature.
Whether the present invention is configured as a child-resistant closure, as a tamper-evident closure, or as a combination of the two, each of these various configurations includes unique structural features and characteristics which are not found in any of the listed patent references.